Dreaded 2 inch mark

M

M forge

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May 27, 2011
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I was hand sanding a blade the other day and thought I would never get out that dreded 2 inch mark. I have not made a lot of knives, maybe 20 or so, but I still often get the dreaded 2 inch mark. I thought I was being careful to avoid this. I gring pretty aggresive with a good bit of pressure before HT, but leave my blades thicker than most for HT. After HT I obviously grind with much less pressure and dunk the blade often, but still seem to always have at least a bit of the dreded mark.

What do you guys do to avoid this? I know prctice will obviously help. I need more, I have only made just over 20 knives in three years.

Thanks
 
Well, here is just an observation. If the steel is harder why would you not grind at least as aggressively as when it is soft? As well since you know the 2" line is there I'm suggesting since you didn't take it out before heat treat, you now need to use a 120 or even 60 grit belt after heat treat. You are still going to be faced with that initial blade contact with belt. I believe it's going to, just mean a lot more practice. Get some mild steel and go to it. It's hard to overcome because now you want to just go to a very soft touch which won't either have control. Keep trying ! Frank
 
If you can watch Harvey Deans video on flat grinding he shows how to avoid that 2" problem.

Basically keep the one side of the blade slightly elevated off the belt as you grind from the ricasso to the tip. So the blade is not totally flush with the belt and you will avoid that ding at the 2" mark.
';
 
I guess I should have noted I do not know the mark is there even before HT. I usually take the blade to 280 grit before HT. I don't grind as aggressively after HT so I don't get the blade too hot. Before HT I start with a 36 and really lay into it, then 120, then 280. After HT I usually go back to 60 and work my way up. It is not until hand sanding that I see that last bit of the 2 inch mark.
 
If you're flat grinding you can learn to finish grind lengthwise, that gets rid of a lot of little flaws like that. To try this you need to round over the top of your platen, remove your top wheel and run really slow. It takes a bit of practice, but it's a big time saver.


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This is a good time to have a disc sander. I'll go between the 36 grit on the 2 x 72 and the 150 grit on the disc. You can see instantly where the dips and dives are so you can take corrective measures on the belt. A new 36 grit ceramic can dig one heck of a trench in a hurry with the wrong pressure. Practice really helps to overcome this irritation.
 
Nathan great idea. I spent a day with Jim Crowell and he had a set up he made for his Bader that was very similar. However the platen got very hot, very fast. Right after using it I thought I have heard of this guy Nathan that could probably help with this. I think maybe one of your water cooled platens could be the ticket for this. I just haven't gotten to this yet. I just don't get to spend the time I need in my shop.

Fred the disk grind would also be awesome. I have looked and wanted one for a while. Would you recommend the flat or 1 degree. All the goodies I want for knifemaking. But I have a kid in college and next year I will have 2 there. Maybe I just need to figure out how to sell some knives. Or get a night job. I already know which would pay more, but I really like knives. LOL
 
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